A portable sound equipment means a sound device having an earphone and a microphone combined with each other and configured to receive an audio signal from a terminal and transmit the sound information collected via the microphone to the terminal. The portable sound equipment is often called the earset. A conventional portable sound equipment is usually a wire type configured to receive an audio signal after linked with an ear jack of a terminal unit via a terminal. In recent, there are increasing demands for wireless communication type wireless sound equipment because of mobility and usability.
The portable sound equipment may be classified into a stereo type with earbuds wearable on the right and left ears and a mono type having one earbud wearable on only one ear. In another aspect, the portable sound equipment may be classified into a kernel type configured to be inserted in an external auditory meatus and an open type wearable, not inserted in the external auditory meatus. A wireless portable sound equipment is carried in a state of being worn on the body part in when not used and the portability is put into operation.
The human right and left ears are different from each other in a shape so that the shape of the left earbud is different from that of the right earbud. Since the ears are usually different for each user, the shapes of the earbuds are not likely to be fitted to some users. In case of the kernel type configured to be inserted in the ear, the angle between an outer surface of the ear and the external auditory meatus plays an important role in determining the wearability.